This study is undertaking an in-depth analysis of mechanisms by which inhaled materials elicit acute and chronic interstitial lung injury. Particular emphasis is placed upon immunologic modes of injury, induced in sensitized animals following aerosol challenge with antigens or phytomitogens. It is anticipated that such studies will define the respective roles of immediate as well as delayed hypersensitivity reactions. BIBLIOGRAPHIC REFERENCE: Willoughby, W.F., Barbaras, J.F., and Wheelis, R. (1976). Immunologic Mechanisms in Experimental Interstitial Pneumonitis, Chest 69: 290.